Why Some People Do Not Have Hip Dips
The Anatomy of No Dip
People without visible hip dips have one or more of: a narrow pelvis (smaller lateral gap), a short femoral neck (trochanter sits closer to pelvis), a low femoral neck angle (trochanter sits more medially), or higher body fat (more cushioning over the gap).
It Is Not About Fitness
A person without hip dips is not healthier, fitter, or stronger than a person with them. They have different bone geometry. That is the entire explanation. The cultural conflation of hip dips with fitness or health is incorrect.
It Can Change
Some women who did not have visible hip dips at 20 develop them at 40 due to fat redistribution and skin laxity changes. Some women who had visible hip dips at 20 lose visibility at 30 due to muscle gain from consistent training. The feature can appear or disappear over time even though the bones do not change.